適用於CMOS製程之高慢波係數共平面帶線及其在濾波器之應用

Abstract

本文提出一種適用於標準CMOS製程的新式傳輸線結構─高慢波係數共平面帶線，並將其運用在濾波器之設計。

本設計藉由同時增加傳輸線單位長度電感值及單位長度電容值，可在不改變傳輸線特性阻抗下，大幅降低訊號傳輸之相位速度，亦即大幅降低波長，可縮短70%以上傳輸線長度，亦即減少佔用晶片面積。此外，波長的縮短，亦使得單位波長之損耗大幅降，而使得本設計之傳輸線可用來實現小面積、高品質之電路。

此新式傳輸線為一週期性結構，藉由調整週期結構單元，可改變傳輸線截止頻率，故傳輸線本身即可用來設計低通濾波器。此外，本文利用此新式傳輸線設計一40GHz電容耦合共振帶通濾波器，特點在小面積、小基板損耗、及適用於標準CMOS製程，其佔用面積僅有72*400um2，最小介入損耗(Insertion Loss)為1.4dB，和目前所發表之濾波器比較面積大幅縮小，品質亦顯著提升，更因不需任何後製程而節省了製造成本。

This thesis presents a novel transmission line─ high slow-wave-factor coplanar stripline (HS-CPS) and exploits the new structure to filter applications.

In the HS-CPS structure, the distributive inductance and the distributive capacitance per unit length are enhanced simultaneously and consequently the slow-wave characteristic can be increased significantly, while the characteristic impedance can be remained the same. The wavelength reduction of above 70% in the HS-CPS indicates the above 70% occupied area can be saved as compared with the conventional coplanar stripline. In addition, the total attenuation decreases as the length is reduced.

The HS-CPS consists of several identical cells, and the cell length determines the cutoff frequency. Therefore, a lowpass filter can be realized simply utilizing the HS-CPS itself. For further application, a 40GHz capacitive coupled one-resonator bandpass filter has been designed and fabricated utilizing the HS-CPS. This bandpass filter features in small size, low substrate loss, and suiting for standard CMOS technology. The occupied area and minimum insertion loss are 72*400um2 and 1.4dB respectively. As compared with the other presented on-chip filters, it is extremely a cheap, miniature, and high-performance solution.